The outer disk is B: selling at the selling price, which is generally considered to be active buying and bullish;

The inner disk is S: the transaction is made at the purchase price, which is generally considered as active selling and short selling.

But this is not necessarily the case: for example, if someone sells a stock with a big gap (or seals the daily limit), after he hangs up the order, the orders that have been closed will be displayed off the market one after another, while the actual stock price is falling strongly.

In addition, the display of general futures market software is every few seconds, and there are often more than one transaction displayed each time. B or S shows the transaction of the last transaction.

Therefore, B and S should be flexibly referenced.